Field of the Invention
The present invention relates to a sheet feeding apparatus and a printing apparatus, and more specifically, to a technique for performing sheet feeding by separating stacked sheets from one another using a plurality of separation parts that apply different levels of resistance to fed sheets.
Description of the Related Art
Sheets used for printing apparatuses such as printers, copy machines, and facsimile machines range from low-rigidity sheets such as plain paper to high-rigidity sheets such as photo paper and postcards. A sheet feeding apparatus has been desired which appropriately feeds such a variety of sheets. Japanese Patent Laid-Open No. 2011-148622 discloses a sheet feeding apparatus that performs sheet feeding by separating sheets from one another using a plurality of separation parts that apply different levels of resistance to fed sheets. More specifically, the sheet feeding apparatus includes the separation parts that are movable with respect to a fixed separation slope and that apply the different levels of resistance based on biasing by springs. When one of the high-rigidity sheets is separated from the other sheets, both the separation part with lower resistance and the separation part with higher resistance are pushed in by the feeding of the sheet and sink into the fixed separation slope, which then allows the sheet to be separated. In this feeding configuration, in particular, when one of the high-rigidity sheets is separated from the other sheets and fed, a load on the sheet is reduced to enable the sheet to be appropriately fed.
However, in the sheet feeding apparatus disclosed in Japanese Patent Laid-Open No. 2011-148622, when a bundle of plurality of low-rigidity sheets enters the separation slope, the plurality of separation parts is pushed in against the force of the bias member and sinks into the fixed separation slopes. Thus, even the lower-rigidity sheet is separated by the fixed separation slope, resistance needed for the desired separation fails to be applied to the sheet, resulting in overlap feeding.